wilkes



A. L. WILKES.

E LECTRIC FURNACE CONTROL, APPLICATION FILED lUNE I7. 1919.

1,377,951 Patented May 10, 1921.

3 SHEEIS-SHEET l zz E A WW A. L. wuxss. ELECTRIC FURNACE CONTROL.

APPLICATION HLED JUNK IT. I919.

1,377,95 1 Patented May 10, 1921.

- 3 $HEET3SHLET 2.

A. L. WILKES. ELECTRIC FURNACE CONTROL.

APPLICATION FILED JUNE l1 919.

Patented May 10, 1921.

3 SHEETS-SHEET 3. i?

.15 rial 1%.:314358, and isparticularly directed UNITED STATES 1. or .LOS months, oanrronum' -isavs fr z:

T To all atoms-my 3 throughout the processin order to obtain the of the invention to provide "a' centre? that willbe' sim le, accurate and-relia 1e.

= Boil} knewn that I, Amm W 'citlzenof the United States, residing at Los ele's, inthe county of Los Angeles, State of alifdrniaQhave'inventcd new and useful Improvements in Electric-Furnace Controls, of which the-following' 'is a specification.

The*-present-invention relates to; a control systemfor electric ovens and it is an object stem The inventionas to do with apparatus of the eneral character set forth in my copen g ap licatio'n entitled Heat control for electric nace, filed August 2, 1919,- Seto -Eroyide a control for electric dentalovens alt ough'itymay -be applied to any electric oven oi the {same eneral character. For the purpose of clear y dividin' the subj ectmatter of this application an that of said a plication this ap lication has f copending been directs to {time control or the heating'means (5f the even while said cope'nding application'=has 'been directed to temperature controh' In d'entalovens the electricity is not fully turned; on. and the even allowed to heatu immediately but the heat must be controlled in such a-manner as to cause the oven :to heat gradually and remain at certain tem eratures -for definiteperiods of time. 1 en'the oven vhas reached a maximum temperature it is necessary that it should "be turned 01f and allowed to cool.

This heat control is necessary in dental ovens I 3 in order to properly bake the'porcelain used in dental work.

. Heretofore electric dental ovens have been provided with resistance controlled by hand to control the heat of the oven and the temerature during the rocess has been shown 'y pyrometers. Wit this arrangement it is necessary'to carefully watch the pyrometer in order to keep the oven at the roper temperature "and the time must e watched desired results; The process of baking porcelain in such an oven becomes expensive due to the factith'at an operator is necessar for the'oven'throu' bout the process whic extends over consi erable len h of time. As well as being expensive this recess is more'or less inaccurate as it is ependent upon the attention-and accuracy of the operator. I

I have by my invention provided a mecha- ,Etncrmc-rtmNAcE ooni-non' 4 nism that will automaticallyf regulate the heat of the oven throughout the process and turn the oven elf when the process is completed. A feature-of the'invention is that it is entirely automaticand n'o attention after-it has been start 41 The mechamsm may-be set so as'to regulate-the heatin the oven inany desiredmanner and'it may be set so as to tum'the oven' ofi wlien-fit reaches any-desired tem" eraturetm Man features-of the ventionas welhas its pre and constructioii will be clearl :understood from thefollowing detail description of at ical form-o the-invention throughout which reference -is -'h-ad to" the accompanying drawings, inwhich-- Figure 15s a plan' new-01E the oven; 2 is an enlarged'detailed section of the mam switch taken as indicated b line 2-2 .on Fig. '1; Fig. 3 is an enlar detailed section taken as indicated by e-3'-3 on Fig.1;

Fig. 4: is an en1ared plan view-of'ithe parts shown'in 3; ig. end view of the oven taken asindicated byline-5% oI'rFig. 1; Fig. -6 is a'wirin' diagram showing the electrical modified wiriii 'system;I Fi 8. is a plan view of a -mo' ified term 0 constructloxr; Fig. 9 is anenlarged detail view show' the detailed construction of l-the modified cm of the dial; Fig. 10 is an enlarged detailed view of a portion of the pyrometer; F1g.-211 shows a snn'plified form of theinventlon'; and Fig. 12' is an enlarged detail section taken as indicated by line 12-12 on Figfill.

Throughout the drawings the invention is shown in connection with a typical electrical dental oven. In the drawin the numeral 10 designates a base upon'wl'nchds mounted a resistance box 11 an oven 12 and acontrol system; Figs? 1s 'a diagram of-a mechanism 13. I The control mechanism a ounted on the side of base 10, as shown in Figs. 1 and5, there is a clock mechanism 17 on which is mounted a dial 18. The mechanism 17 is preferably an'ordinary clock mechanism which may be wound by a key 19 set by a screw 20 and regulated by an arm however I do not wish to myself to this particular formoi rnecha nism as it is obvio'u s' th'at other mechanisms could be readily adapted to accomplish the, same results. The dial 18 is mounted'on'th'e clock mechanism by means of a screw '22 which coii 'ierates'-with spring washer '23. This construction holdsthe dial m firmly on the clock mechanism and causes itto be ro- The bellcrank .27- :is :50 arranged .;that ;the

.end of arm- 28 engages the peripheryzof: fdial l8..l-.=l?-ivotally connected at 30 tofthe end of arm 29 is aconnectin I'Od:3l' whicl1 'is'-car=- .riedin a-bracket32. he connecting-rod 31 connects the farm 29-toa block? 33 which is mounted. ona portio'n of controliarm fis-as hereinafter; described. :At the-outer endz-of control .i-arm .14 there is an ,enlar edport-ion 34:. Theenlargediportion 34 an -the slot 35 in it; are curved: so as: tOybQ concentric with pivot :15. The: slot 35 beingIcut? in enlarged poi-6011134 forms-a curved portion 36-uround which is mounted 'hlOck 33. On the-:iipper surface of portion '36:- are-ratchet teeth 37,

' clearlyis'hownein L3; The blok- 33*is made intwd parts 37-and 38-which arehel'd together bymea'ns of-screws 39.-. :The block 33 is constructed .in this :ma-nner' so that :it may be mounted around portion 36. Mount ed within the block 33:-.on-a-.pin 4:0, .which-is mounted in portion'37 of theiblookg is a pawl 4.1. "The end -of.=pawl .41 engages ratchet teeth 37 =and'is held in engagement'with said teeth b ymeans of a spring 42 which extends between ortion'38 and pawl 41,"a -s shown in Fig. 3. xtending "from pawl-.41 through block 33is a pin 41' on: whlch is a knob-.41.

This proj ectlon from the pawlv provides means by'which the pawl may be disengaged from the ratchet teeth thus makinq it possible to move'control arm .14 freely. --The end-of connecting rod- 31 forms; a-yoke 44 which fits over the block 33. The yoke-His pivotally connected to the block 33. by means of:pivot pins 45 which are screw threadedly engaged in block 33. Between the bracket 32 and the arm 29there is a spring 46 which tends at all times to keep arm 28 in contact with dial 18.

I When the clock mechanism 17z causes the dial 18 to rotate in the direction indicated by the arrow in Fi Ithe arm 28 will drop into a notch 24. his movement of arm 28, which is one arm of the bell crank 27 will cause movement of connecting-rod 31 in the direction indicated by the-'ar-row in-Fig. 1. en connecting rod 31 is moved it will carryfwith itblock 3-3, and-blockr33 will carry with it the control arm :14, due to the with the pawl enga ratchel The mecha'n i srn is es1gned and proportioned so as to cause -the--inevh1ent of arm 14, caused Joy theiallmg of arm 28 into a notch 24, to

'h'e'gr'eat enough to move control arm 14 a distance of one contact. As the dial 18 continues-to'i'otate the arm 28 will beg-railwa pushedput Thi s..movement will cause the connecting"rod 3l 'and the block 33 to be moved back to. .t h e. .positiomin yghi ch-they were :beforggthe a rm' 28 had fialleng nto the 2 Bn .thsmoyeinent will-n t cause control arm let be moved, due to thelilfact,

.that pawl iwill-merely slidemlflli ratchet .9

e th 37 As. he d 8 q inus ..to;r a e e.-. .2

co e .=z wit the wariou t hssfi e -the: rol will." her bytem v d-acmssthe c aatsvlfi until ifihas-reached the last/one..-v

the control arm; n is :in this: posi ion the current from-dead wires .50'is passing. directlyztor-the'voven; withou passing through resistance iii be; '11. The2.Qven.;w1lL ;rise-.;m

mp ure sand the temperat re ab '2 I registered; by fhandzfila ofipyrometerisaithe lead wi-res. 53-. Qfl Wh'lQ w enter -ii.1e..;ovenl Mounted .on the; yrometer, nsshown: Fig. IOtheBe-isanTa fiustable ar 54x13 The;ar'm

54niijs;carried in iaiboss 5500 thc sidozof the pyrometen and -is.\'=ad5nstah1e tin; said-boss .The :arm 54; a set in ithepy'rometer so: th t the hand 51*.wgilhengage. 1t.- :='I he=ar1'n is adj'usted'in .boss 55:11Iltildlt5fi1id fifi isieven graduation on -the .pyrometer, Fat 21' which it is, desired to turn. the, oven off. Arm 54 is set in this position. by means of a set screw 57. .-When the pyrometenhand 51 has come in contact with the arm .56 the. main switch 58 of the oven isrthrown out. 1; Fig.6 is. a diagram of the means for-accomplishing this operation. ':When the hand-fil engages arm-56 theacircuit 60, energized by. abattery 61, is closed-,:and.-.relay 62' closes circuit .63

which inparallelrwith the rheostatR {the resistance hereinbefore referred ;to con-1 trolled by controller arm 14).; .;.-The closing of-circuit 63-eauseselectromagnet: 64 to be energizedtgj'lhe electromagnet K54 moves-the lever 65; which is pivoted-mt 66 to a bracket 67, in the direction indicated by the arrow in Figs; 2. and'6. This movement of lever 65 disenga es it from pin 68 which is mounted on the lade 89 of the. main cut out- Switch S. The blade-69 is pivotally mounted std-0 on. a;.=b1:acket 71 land: engagescontaicts 72. Connected betweenithe-end 7350f blade 69 and base 10. therei's a-spring 7a which tends at all times to holdtheswi-tch open, thatds, keeps blade 69 out ofqement with contacts- 72; rAsrsoon as the lever. 65 isiiisem gaged from, pin 68:blade 69-is disengaged from contacts 72 by the action of.spring:741.- The throwing open of switch 58 opens the circuit to the oven and thus being further heated.

prevents it from Thesystem of turning ofi the oven just described,'is a typical'way in which it may 'be'done and it will-be-understood that the invention is notlimitedto this particular -arrangement as the oven could'be shut ofi in 'many difierent ways. For instance, as

shown in Fig. 8, a fuse 90 may be connected in'a lead-wire 50 and 'placed in the oven so 'as' to become heated by the oven. The fuses may be made of a metal'that will melt at the desired temperature but large enough not to become heated by the? electricity passing through it. With this form of the invention,'wl 'n 'it' is desired to turnthe'oven oil at a certaintemperature a fuse thatwill melt at that temperaturemay be placed in the ovenF When the temperature of the oven has reachedthis 'point'jthe fuse will melt and Y thereby ;'-brea kf""the circuit. Although this system is very sim 'le it is not'as accurate as the system first escribed the entireperiphery-offthe-dia and between said notches are arms "8%1pfvotally mounted by means of screws 80. e arms "81 have a curved surface '82 which'is of the same curvature as the outer peripher'ybf the dial. As shownin Fig;-.g9,thearms 81 may be turned to a position m which they closethe slots and form an even surface on which the arm 28 may ride or they may be thrown to a position which allows any notch or notches to be open. With this form of construction, the dial bein made relatively large and the notches small and close together, it is possible to set the dial so that it will accurately control the process.

In the dial first described, the notches were of such a depth as to cause the movement of control arm 14 from one contact to the next. In the dial shown in Fig. 8 and Fig. 9, each notch 24* is of such a depth as to cause the arm 28 to fall in just far enough to cause movement of the mechanism suificient to move control arm 14 from one contact to the next. But however, the portion 36 of arm 14 has only one ratchet tooth 37" for each contact point so that the movement of the arm 28 into a notch 24 will be just enough to catch one ratchet tooth. In this form of device in order to assure positive action and to be sure that the pawl has engaged the ratchet tooth, the arms 81 have rounded portions 81 which, when the arms are turned so as to open the notches, will project beyond the periphery of the dial. When the arm 18 passes over the rounded portion 81 it causes the entire mechanism to be moved back slightly more than the required distance. hismakes the engagement 0 pawl and ratchet tooth certain.

In Fi 11 and is'a form of the invention which greatly simplifies the construction. In this form of the invention the control arm hithe-rheostat R is removed-and a brush "100'is'mounted at 15 in its stead. The brush 100 engages a commutator 102 on the shaft 103 of the clock mechanism 17 ,the brush iskept'in contact-with the commutator by a 5 ring 100. The commutator is not mounte ;.directly on the shaft but is mountedon afiber bushing 104 which forms an insulator between the commutator-and the shaft. "Extending from commutator 102 there is an arm 105 on the end of which is mounted a brush 106." The brush 106 engages contacts 107 which are mounted in a circular fiber block 108. Block 108 v is mounted'on the'clock mechanism 17. Clock mechanism 17 maybe the same as the clock mechanism {-17 which is used in the other form of the invention. The contacts are mounted in theblock in such a manner as to be separated from each other and to form notches between adjacent contacts which will cause brush 106 to slide ofiof onecontact directly 'onto 'the' next. This makes the changing ofthe brush from one contact to the nextfvery uick; Connected to contacts 107-there are inding posts 110 which extend through" slots 110 in block 108. The contacts are mounted in block 108 as shown in Fig-11: Bymoving the bindin posts in slots 110 thecontacts may be a justed so as to be in-contact with'brush 100 anyde- .sired lengthof' time." Extending between the binding posts 110 and the contacts 16 are wires 112.

The mechanism just described completes the circuit between the point 15 and the various contacts 16. contacts 16 are connected up (as shown in Fig. 11) so that the rotation of the brush 106 due to the clock mechanism 17" will cause resistance to be gradually out out.

The various arrangements and the details of construction hereinabove described are merely typical embodiments of my invention and therefore I do not wish to limit my self to them but wish to reserve to myself any changes or modifications which may appear to those skilled in the art or fall within the sec e of the following claims.

Having described a preferred form of my invention, I claim:

1. In combination with an electric oven, means for varying the temperature of said oven,time regulated means for actuating said varying means, and means for automatically disconnecting said oven upon reaching a predetermined temperature.

2. In comb'nation with an electric oven,

The contacts 107 and means embo ying mechanically voperated connecting means for -sai d-res1stance.-.;5;., =5

a 4. In combination with an 'BIGCtI'IC-OVGH .meansforvarying the'temperature of said oven,.' said' means embod E variable re sistance, and time :re ated means for actuating said -varying means, said regulating means embodying a mechanically rotated arm adapted to engage contacts, said arm and contacts being 111' con'nectionwith said resistance.

5. In combination with an electric oven, means for varying the1.te mperature.o, said oven, said means embed 'ng variable resistance, and timeregulatedimeans tor-actuate ing said varyin'g means, said; regulatin means embodying a mechanically rota arm adapted toengage adjustable contacts, said arm and contacts -beingi in connection withsaid resistance. 1' a 6. In combination, with-an electric oven, means for varying the temperature .o f said oven, time regulated means for actuating said varyi qf'means, and means for'automatically connecting said -oven upon reaching a predetermined temperature, said means embodying a pyrometer arrangedto actuate a switch. i

7. In combination -withan electrically heated oven, time controlled. means for varying the heating, current, said means embodylng a rheostat with a movable contact arm and time mechanism tomove said arm step by step, and temperature controlled meanslfor entirelycuttin off such current. 8. In combination wit an ielectrically heated oven, time controlled means for varyinggthe heating current, .said means em- .bodymg a rheostat witha movable contact arm and time mechanism to move-said arm .step,-by step, and temperature controlled means 'for entirely cutting'ofi such current, said means embodying a switch in the main circuitleading to the oven, and-pyrometer controlled mechanism for-causing said switch a the oven and arranged to have a moving 7 part in an actuating circuit and adapted to cooperate with an adjustable contact.

In witness that I claim the foregoing I have hereunto subscribed my name this 11th day, of June,-1919. -v

v v ALFRED L. WILKES. =Witness: VIRGINIA Bnnmcnn. 

